Perception of temporally ordered visual stimulation will be studied by psychophysical methods, over the extent of the binocular visual field. Interocular and interhemispheric thresholds and biases in temporal-order-dependent perception will be investigated in normal observers of different age groups, as well as in patients with conditions which can affect conduction times and/or processing the temporal order of binocular stimuli. The program has two main objectives: 1) investigating spatiotemporal relationships in the normal binocular field (specific questions: is temporal disparity equivalent to spatial disparity in the absence of correlated stimulus velocity?; is the stereoscopic threshold inversely related to critical exposure time?; is relative stereoscopic depth scaled according to relative height?; what is the increase in latency with eccentricity and is it isotropic in left-right and up-down comparisons?; and 2) developing a method of "temporal campimetry" to aid in neuro-ophthalmological diagnosis (two main questions: which anisopias produce a related bias in interocular visual latency?; do specific "temporal scotomata" appear at an early stage in those neurological conditions which are manifested eventually through conventional field defects?). It is known that the central nervous system does not compensate for differences in conduction times, and previous work has shown that such differences can be determined in the dichoptic mode of stimulation. The program is, therefore, both promising and realistic.